Liquid compositions containing soluble boron have become increasingly popular in the last few years, primarily because of convenience of use in application to plants and soils and also for their ease in blending with other agricultural compositions, such as fertilizers and pesticides.
Boron is an essential micronutrient which is required by many crops and is therefore blended into many commercial fertilizer formulations, both liquid and granular. It may also be used in liquid form as a foliar spray, to be applied to boron deficient crops and absorbed through the leaves.
Previously, liquid boron compositions were usually prepared by merely dissolving an inorganic borate such as the sodium borates in water. However, the relatively low solubility of the sodium borates limits the amount of boron in the aqueous solution to less than about 3%.
Recently, workers in the plant food art have proposed various liquid compositions containing boron at a level which is generally somewhat higher than that obtained by merely dissolving sodium borates in water. For example, Ott U.S. Pat. No. 4,332,609, describes a liquid fertilizer composition containing a polyborate compound which is formed by reacting boric acid with an alkanolamine or aliphatic polyamine. These compositions have a substantially higher amount of boron, but tend to be inconvenient to prepare and are relatively expensive.
Similarly, Howard U.S. Pat. No. 4,572,733, describes preparation of a boron composition for agricultural application, which involves first forming a solution of a boron compound such as the sodium borates in a water-miscible glycol solvent, dispersing fine particles of a second boron compound in the glycol solution and then grinding or micronizing to form a flowable composition containing a fine slurry of the borate.
U.S. Pat. No. 4,155,739, to Downer et al., describes a boron containing spray oil for use as a foliar application. The boron can be present in several forms but is based on various types of borate esters. Amine-borate adducts are described but it is clear that these are adducts prepared by reaction of a triester of boric acid with a complex high molecular weight amine. The boron content in the spray oils is relatively low, generally in the rang of from 0.01 to 2% weight/volume.
Aqueous mixtures containing soluble boron have also been proposed for other uses such as, wood preservation and corrosion inhibition and in cutting fluids. For example, Gottsche et al. U.S. Pat. No. 4,461,721 describes a wood preservative which is an aqueous paste containing boric acid, organic amine and sodium polyborate. Sluhan U.S. Pat. No. 2,999,064 describes an aqueous cutting fluid composition containing a boric acid-alkanolamine reaction product which preferably also contains a long chain unsaturated fatty acid. Sluhan U.S. Pat. No. 3,186,946 and King U.S. Pat. No. 3,719,598 are also directed to cutting fluid compositions which contain amine borate salts in which the amines are complex alkanolamines or alkanoldiamines.
Vukasovich, Lubrication Engineering, Vol 36, 12, 708-712 (December 1980), and Vukasovich, 3rd International Colloquium, "Lubrication in Metal Working, Machining and Metal Forming Processes", Jan. 12-14, 1982, Technische Akademie Esslingen, Nellingen FDR, describes the effects of sodium molybdate in synthetic metal working fluids including "commercial amine borate-based" concentrates, which appear to be the alkanolamine borates of the Sluhan and King patents described above.
Canadian Patent 1082230, to Anger, describes polyborate solutions prepared by reacting alkanolamines or aliphatic polyamines with boric acid. These compositions are described as being useful as textile auxiliaries such as yarn moistening agents, as metal working agents and for liquid cleaners and disinfectants.
Davis et al. U.S. Pat. No. 4,119,552 discloses the use of alkylammonium borates as boronating agents for preparing complex boronated alkylphenoxy alkanoic acid amide lubricant additives.
Other patents of interest are German patent specification 21 40 051 to Gottsche which describes boric acid-amine compositions in water, as well as U.S. Pat. No. 2,492,562 which describes preparation of a sulfurization catalyst for fatty oils. The catalyst is prepared by heating a boro-ethylene glycol complex with a primary aliphatic amine containing at least 10 carbon atoms at an elevated temperature to give a catalyst which is a waxy-solid material.
See also U.S. Pat. No. 4,007,029 which describes liquid fertilizer compositions based on anhydrous ammonia solutions of a trace element, which may include boric acid.
Further, European Patent Specification 0 046 380, describes a liquid wood-treating composition, consisting of a solution of boric acid in ethylene glycol, which may optionally contain water.